A wheel loader that is a self-propelled work vehicle includes a traveling apparatus that causes a vehicle to travel and a work implement that performs various operations such as excavation. The traveling apparatus and the work implement are driven by driving force from an engine.
An operator of the wheel loader simultaneously operates an accelerator pedal and a boom lever at the same time when soil scooped by a bucket of the work implement is loaded on a cargo box of a dump truck. Consequently, the wheel loader advances and performs boom raising. A loading operation is also referred to as “dump approach”.
In the loading operation, when a distance between the wheel loader and the dump truck is insufficient, the wheel loader may arrive in front of the dump truck before the bucket is raised higher than the cargo box of the dump truck. For this reason, the operator adjusts time until the wheel loader arrives near the dump truck by operating not only the accelerator pedal but also the brake pedal in consideration of time necessary for the raising of the boom.
WO 2009/116248 (PTL 1) discloses a work vehicle including a modulation clutch connected to a distributor that distributes output from the engine into a traveling system and a hydraulic device system. When the loading operation is detected, the work vehicle performs control for reducing hydraulic pressure of the modulation clutch. In particular, the work vehicle controls the hydraulic pressure of the modulation clutch according to an operation amount of the boom lever and an operation amount of the accelerator when the loading operation is detected.
U.S. Pat. No. 6,162,146 (PTL 2) discloses a technique relating to a drive train (powertrain) of the work vehicle such as the wheel loader. The work vehicle of U.S. Pat. No. 6,162,146 has a pressable right pedal that selectively controls torque associated with the powertrain. The work vehicle controls pressure of a selected direction switching clutch according to a pressing amount (position) of the right pedal.